Power tools driven by brushless motors are known. In such power tools, the current conduction angle and the advance angle of the brushless motor are fixed or preset based on typical or expected operating conditions. Japanese Unexamined Patent Application Publication No. 2007-276042 (and its family member US 2009/0160373), for example, discloses a power tool having a brushless motor with a current conduction angle and an advance angle that are preset to fixed values in order to optimize drive characteristics of the brushless motor and power tool.